Load Specifications
Load data in caliber .260 Ackley Improved with .264 | 135gr | TWENTY-NINE ERTP bullet and 97 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Power Pro 2000-MR, Hodgdon Superformance and Alliant Reloder-17.
Important Notice: DO NOT go below Minimum Charge or above Maximum Charge. Since we have no control over the equipment and components used, any responsibility and liability for the results achieved is rejected.
Only powders/loads that match the current filter criteria are displayed: max pressure of a load ≤ 90% of max. standardized pressure, fill rate ≥ 80% and propellant combustion ≥ 95%. Use the sliders above the tables to adjust these thresholds.
Charge: Powder weight in grains. Start with the minimum load and work up carefully.
FR (Fill Rate): Case fill as a percentage. Values above 100% mean compressed loads.
MaxP / %: Maximum chamber pressure in bar and as a percentage of the standardized maximum for this caliber.
V(0): Muzzle velocity in feet per second (fps) at the standardized barrel length.
z (Powder Burn): Estimated propellant combustion percentage at bullet exit.
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You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 84% | 55,405 psi | 89% | 2589 fps | 100% |
| Accurate 2495 | <<locked>> | 88% | 53,969 psi | 87% | 2615 fps | 100% |
| Accurate 2520 | <<locked>> | 84% | 55,898 psi | 90% | 2680 fps | 100% |
| Accurate 2700 | <<locked>> | 88% | 53,011 psi | 85% | 2615 fps | 97.2% |
| Accurate 3100ᴾ | <<locked>> | 100% | 41,017 psi | 66% | 2523 fps | 96.4% |
| Accurate 4064 | <<locked>> | 90% | 53,824 psi | 86% | 2657 fps | 100% |
| Accurate 4350 | <<locked>> | 98% | 53,388 psi | 86% | 2743 fps | 99.7% |
| ADI AR 2206H | <<locked>> | 86% | 54,491 psi | 87% | 2694 fps | 100% |
| ADI AR 2208 | <<locked>> | 92% | 55,521 psi | 89% | 2694 fps | 99.9% |
| ADI Benchmark 8208 | <<locked>> | 84% | 53,330 psi | 86% | 2641 fps | 100% |
| Alliant AR-Comp | <<locked>> | 84% | 54,389 psi | 87% | 2618 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 88% | 53,737 psi | 86% | 2805 fps | 99.9% |
| Alliant Reloder- TS 15.5 | <<locked>> | 92% | 55,535 psi | 89% | 2713 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 90% | 56,173 psi | 90% | 2736 fps | 100% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 54,926 psi | 88% | 2799 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 96% | 56,318 psi | 90% | 2835 fps | 100% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 39,334 psi | 63% | 2552 fps | 99.2% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 43,642 psi | 70% | 2703 fps | 98.5% |
| Baschieri & Pellagri 107 | <<locked>> | 86% | 53,998 psi | 87% | 2707 fps | 99.8% |
| Bofors RP3 | <<locked>> | 92% | 55,941 psi | 90% | 2726 fps | 100% |
| Bofors RP7 | <<locked>> | 96% | 56,333 psi | 90% | 2703 fps | 98% |
| Hodgdon Benchmark | <<locked>> | 84% | 55,158 psi | 88% | 2625 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 86% | 56,159 psi | 90% | 2720 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 82% | 54,578 psi | 88% | 2766 fps | 100% |
| Hodgdon H380 | <<locked>> | 90% | 53,505 psi | 86% | 2694 fps | 99.5% |
| Hodgdon H414 | <<locked>> | 98% | 56,420 psi | 90% | 2792 fps | 98.6% |
| Hodgdon H4350 | <<locked>> | 94% | 53,795 psi | 86% | 2707 fps | 96.9% |
| Hodgdon H4895 | <<locked>> | 86% | 55,085 psi | 88% | 2703 fps | 100% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 51,082 psi | 82% | 2677 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 88% | 54,389 psi | 87% | 2736 fps | 100% |
| Hodgdon Superformance | <<locked>> | 96% | 53,476 psi | 86% | 2776 fps | 97.8% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,636 psi | 57% | 1627 fps | 100% |
| Hodgdon VARGET | <<locked>> | 88% | 56,173 psi | 90% | 2703 fps | 100% |
| IMR 3031 | <<locked>> | 86% | 55,187 psi | 88% | 2684 fps | 100% |
| IMR 4064 | <<locked>> | 90% | 55,114 psi | 88% | 2677 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 88% | 54,940 psi | 88% | 2657 fps | 98.2% |
| IMR 4350 | <<locked>> | 98% | 52,837 psi | 85% | 2677 fps | 97.4% |
| IMR 4451 Enduron | <<locked>> | 94% | 54,708 psi | 88% | 2684 fps | 98.1% |
| IMR 4831ᴾ | <<locked>> | 100% | 54,143 psi | 87% | 2736 fps | 99.8% |
| IMR 4895 | <<locked>> | 88% | 53,882 psi | 86% | 2713 fps | 100% |
| IMR 8208 XBR | <<locked>> | 84% | 53,330 psi | 86% | 2641 fps | 100% |
| Lovex D073.6 | <<locked>> | 86% | 54,201 psi | 87% | 2671 fps | 100% |
| Lovex S060 | <<locked>> | 86% | 54,070 psi | 87% | 2621 fps | 100% |
| Lovex S062 | <<locked>> | 90% | 54,607 psi | 88% | 2671 fps | 100% |
| Lovex S065 | <<locked>> | 96% | 53,867 psi | 86% | 2677 fps | 99.1% |
| Lovex S070 | <<locked>> | 98% | 54,853 psi | 88% | 2710 fps | 98.4% |
| Norma 201 | <<locked>> | 86% | 53,287 psi | 85% | 2641 fps | 100% |
| Norma 202 | <<locked>> | 86% | 53,780 psi | 86% | 2641 fps | 100% |
| Norma 203B | <<locked>> | 90% | 55,332 psi | 89% | 2723 fps | 100% |
| Norma 204 | <<locked>> | 98% | 53,403 psi | 86% | 2723 fps | 96.3% |
| Norma URPᴾ | <<locked>> | 100% | 56,086 psi | 90% | 2779 fps | 99.9% |
| Ramshot Big Game | <<locked>> | 90% | 55,579 psi | 89% | 2746 fps | 100% |
| Ramshot Hunterᴾ | <<locked>> | 100% | 55,143 psi | 88% | 2782 fps | 99% |
| Ramshot TAC | <<locked>> | 84% | 53,621 psi | 86% | 2664 fps | 99.1% |
| Ramshot Wild Boar | <<locked>> | 84% | 53,374 psi | 86% | 2684 fps | 100% |
| Ramshot X-Terminator | <<locked>> | 82% | 54,114 psi | 87% | 2644 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,216 psi | 58% | 1667 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 90% | 53,824 psi | 86% | 2677 fps | 98.6% |
| ReloadSwiss RS 52 | <<locked>> | 86% | 53,040 psi | 85% | 2749 fps | 99.9% |
| ReloadSwiss RS 60 | <<locked>> | 94% | 56,028 psi | 90% | 2831 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 98% | 53,098 psi | 85% | 2766 fps | 99.6% |
| ReloadSwiss RS 70 | <<locked>> | 98% | 52,736 psi | 85% | 2792 fps | 99.5% |
| Rottweil R 901 | <<locked>> | 84% | 54,418 psi | 87% | 2621 fps | 100% |
| Rottweil R 902 | <<locked>> | 88% | 53,780 psi | 86% | 2638 fps | 100% |
| Rottweil R 903 | <<locked>> | 94% | 55,811 psi | 89% | 2720 fps | 100% |
| Rottweil R 907 | <<locked>> | 96% | 56,333 psi | 90% | 2703 fps | 98% |
| Shooters World Long Rifle | <<locked>> | 96% | 53,867 psi | 86% | 2677 fps | 99.1% |
| Shooters World Match Rifle | <<locked>> | 86% | 54,201 psi | 87% | 2671 fps | 100% |
| Shooters World Precision | <<locked>> | 90% | 54,607 psi | 88% | 2671 fps | 100% |
| Shooters World SW4350 | <<locked>> | 98% | 54,853 psi | 88% | 2710 fps | 98.4% |
| SNPE Vectan SP 11 | <<locked>> | 92% | 54,143 psi | 87% | 2733 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 86% | 55,579 psi | 89% | 2694 fps | 99.6% |
| SNPE Vectan SP 9 | <<locked>> | 88% | 56,144 psi | 90% | 2713 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 86% | 54,694 psi | 88% | 2579 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 92% | 54,882 psi | 88% | 2579 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 96% | 54,302 psi | 87% | 2631 fps | 98.1% |
| Somchem S321 | <<locked>> | 82% | 54,462 psi | 87% | 2674 fps | 100% |
| Somchem S335 | <<locked>> | 86% | 54,128 psi | 87% | 2579 fps | 100% |
| Somchem S341 | <<locked>> | 86% | 55,100 psi | 88% | 2680 fps | 100% |
| Somchem S355 | <<locked>> | 94% | 56,217 psi | 90% | 2717 fps | 100% |
| Somchem S365ᴾ | <<locked>> | 100% | 50,734 psi | 81% | 2736 fps | 100% |
| Somchem S385ᴾ | <<locked>> | 100% | 46,934 psi | 75% | 2618 fps | 96.2% |
| Vihtavuori N130 | <<locked>> | 82% | 54,433 psi | 87% | 2539 fps | 100% |
| Vihtavuori N133 | <<locked>> | 86% | 54,955 psi | 88% | 2562 fps | 100% |
| Vihtavuori N135 | <<locked>> | 88% | 53,432 psi | 86% | 2602 fps | 100% |
| Vihtavuori N140 | <<locked>> | 88% | 54,128 psi | 87% | 2618 fps | 100% |
| Vihtavuori N150 | <<locked>> | 94% | 54,070 psi | 87% | 2648 fps | 100% |
| Vihtavuori N160 | <<locked>> | 98% | 55,085 psi | 88% | 2726 fps | 99.8% |
| Vihtavuori N530 | <<locked>> | 84% | 53,780 psi | 86% | 2641 fps | 100% |
| Vihtavuori N540 | <<locked>> | 90% | 55,811 psi | 89% | 2664 fps | 100% |
| Vihtavuori N550 | <<locked>> | 98% | 54,099 psi | 87% | 2733 fps | 99.6% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 43,134 psi | 69% | 2628 fps | 99.1% |
| Winchester 6.5 StaBALL | <<locked>> | 98% | 55,637 psi | 89% | 2710 fps | 100% |
| Winchester 748 | <<locked>> | 84% | 53,809 psi | 86% | 2690 fps | 100% |
| Winchester 760 | <<locked>> | 96% | 53,142 psi | 85% | 2743 fps | 98.1% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 35,215 psi | 56% | 2559 fps | 99.2% |
| Winchester StaBALL Match | <<locked>> | 88% | 56,057 psi | 90% | 2720 fps | 100% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 80% | 49,052 psi | 79% | 2507 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 41,626 psi | 67% | 2438 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 48,776 psi | 78% | 2585 fps | 100% |
| Accurate 2700 | <<locked>> | 82% | 43,729 psi | 70% | 2464 fps | 95% |
| Accurate 3100 | <<locked>> | 98% | 38,101 psi | 61% | 2467 fps | 95.6% |
| Accurate 4064 | <<locked>> | 80% | 39,392 psi | 63% | 2438 fps | 100% |
| Accurate 4350 | <<locked>> | 84% | 33,011 psi | 53% | 2372 fps | 95.8% |
| ADI AR 2206H | <<locked>> | 80% | 45,266 psi | 73% | 2546 fps | 99.5% |
| ADI AR 2208 | <<locked>> | 80% | 38,493 psi | 62% | 2405 fps | 97.9% |
| ADI Benchmark 8208 | <<locked>> | 80% | 47,340 psi | 76% | 2552 fps | 100% |
| Alliant AR-Comp | <<locked>> | 80% | 47,819 psi | 77% | 2533 fps | 100% |
| Alliant Power Pro 2000-MR | 35.9 gr | 80% | 41,147 psi | 66% | 2582 fps | 98.5% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 38,043 psi | 61% | 2428 fps | 99.1% |
| Alliant Reloder-15 | <<locked>> | 80% | 40,973 psi | 66% | 2487 fps | 98.6% |
| Alliant Reloder-16 | <<locked>> | 82% | 31,531 psi | 51% | 2336 fps | 95% |
| Alliant Reloder-17 | 35.3 gr | 80% | 32,808 psi | 53% | 2398 fps | 97.5% |
| Alliant Reloder-23 | <<locked>> | 90% | 28,848 psi | 46% | 2297 fps | 95.6% |
| Alliant Reloder-26 | <<locked>> | 94% | 35,476 psi | 57% | 2523 fps | 95.9% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 44,251 psi | 71% | 2549 fps | 98.8% |
| Bofors RP3 | <<locked>> | 80% | 37,652 psi | 60% | 2428 fps | 99.1% |
| Bofors RP7 | <<locked>> | 88% | 43,656 psi | 70% | 2500 fps | 95.3% |
| Hodgdon Benchmark | <<locked>> | 80% | 49,095 psi | 79% | 2539 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 80% | 46,195 psi | 74% | 2575 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 80% | 50,908 psi | 82% | 2710 fps | 99.8% |
| Hodgdon H380 | <<locked>> | 80% | 38,537 psi | 62% | 2434 fps | 96.9% |
| Hodgdon H414 | <<locked>> | 88% | 40,640 psi | 65% | 2530 fps | 95.3% |
| Hodgdon H4350 | <<locked>> | 90% | 47,413 psi | 76% | 2602 fps | 95.5% |
| Hodgdon H4895 | <<locked>> | 80% | 45,730 psi | 73% | 2559 fps | 99.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 27,224 psi | 44% | 2195 fps | 95.1% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 41,698 psi | 67% | 2533 fps | 99.7% |
| Hodgdon Superformance | 42 gr | 90% | 43,221 psi | 69% | 2598 fps | 95.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,368 psi | 42% | 1450 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 43,888 psi | 70% | 2513 fps | 99.6% |
| IMR 3031 | <<locked>> | 80% | 45,252 psi | 73% | 2543 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 40,422 psi | 65% | 2438 fps | 98.6% |
| IMR 4166 Enduron | <<locked>> | 80% | 42,815 psi | 69% | 2457 fps | 95.7% |
| IMR 4350 | <<locked>> | 92% | 43,918 psi | 70% | 2530 fps | 95.4% |
| IMR 4451 Enduron | <<locked>> | 86% | 42,960 psi | 69% | 2487 fps | 95.6% |
| IMR 4831 | <<locked>> | 84% | 32,155 psi | 52% | 2336 fps | 95.5% |
| IMR 4895 | <<locked>> | 80% | 41,959 psi | 67% | 2516 fps | 99.2% |
| IMR 8208 XBR | <<locked>> | 80% | 47,340 psi | 76% | 2552 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 44,396 psi | 71% | 2526 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 44,962 psi | 72% | 2480 fps | 99.5% |
| Lovex S062 | <<locked>> | 80% | 40,147 psi | 64% | 2438 fps | 99.6% |
| Lovex S065 | <<locked>> | 84% | 37,507 psi | 60% | 2388 fps | 95.7% |
| Lovex S070 | <<locked>> | 88% | 40,103 psi | 64% | 2461 fps | 95.3% |
| Norma 201 | <<locked>> | 80% | 44,164 psi | 71% | 2497 fps | 99.9% |
| Norma 202 | <<locked>> | 80% | 44,498 psi | 71% | 2503 fps | 100% |
| Norma 203B | <<locked>> | 80% | 40,379 psi | 65% | 2477 fps | 98.9% |
| Norma 204 | <<locked>> | 96% | 49,835 psi | 80% | 2667 fps | 95.5% |
| Norma URP | <<locked>> | 84% | 33,620 psi | 54% | 2379 fps | 95.8% |
| Ramshot Big Game | <<locked>> | 80% | 39,871 psi | 64% | 2490 fps | 98.7% |
| Ramshot Hunter | <<locked>> | 88% | 37,173 psi | 60% | 2461 fps | 95% |
| Ramshot TAC | <<locked>> | 80% | 47,094 psi | 76% | 2559 fps | 98.2% |
| Ramshot Wild Boar | <<locked>> | 80% | 46,746 psi | 75% | 2579 fps | 99.7% |
| Ramshot X-Terminator | <<locked>> | 80% | 50,749 psi | 81% | 2595 fps | 99.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,977 psi | 43% | 1490 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 38,885 psi | 62% | 2415 fps | 95.3% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 43,192 psi | 69% | 2589 fps | 99% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 34,954 psi | 56% | 2461 fps | 99.8% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 32,793 psi | 53% | 2388 fps | 95.2% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 35,215 psi | 56% | 2448 fps | 95.2% |
| Rottweil R 901 | <<locked>> | 80% | 48,327 psi | 77% | 2533 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 42,293 psi | 68% | 2457 fps | 99.8% |
| Rottweil R 903 | <<locked>> | 80% | 35,534 psi | 57% | 2379 fps | 98.5% |
| Rottweil R 907 | <<locked>> | 88% | 43,656 psi | 70% | 2500 fps | 95.3% |
| Shooters World Long Rifle | <<locked>> | 84% | 37,507 psi | 60% | 2388 fps | 95.7% |
| Shooters World Match Rifle | <<locked>> | 80% | 44,396 psi | 71% | 2526 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 40,147 psi | 64% | 2438 fps | 99.6% |
| Shooters World SW4350 | <<locked>> | 88% | 40,103 psi | 64% | 2461 fps | 95.3% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 36,521 psi | 59% | 2428 fps | 98% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 45,353 psi | 73% | 2536 fps | 98.3% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 43,743 psi | 70% | 2520 fps | 99.3% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 45,484 psi | 73% | 2448 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 37,855 psi | 61% | 2323 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 41,800 psi | 67% | 2431 fps | 95.5% |
| Somchem S321 | <<locked>> | 80% | 50,981 psi | 82% | 2625 fps | 100% |
| Somchem S335 | <<locked>> | 80% | 45,063 psi | 72% | 2451 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 45,034 psi | 72% | 2530 fps | 99.5% |
| Somchem S355 | <<locked>> | 80% | 36,274 psi | 58% | 2382 fps | 98.4% |
| Somchem S365 | <<locked>> | 80% | 26,440 psi | 42% | 2228 fps | 96.3% |
| Somchem S385 | <<locked>> | 98% | 44,135 psi | 71% | 2572 fps | 95.5% |
| Vihtavuori N130 | <<locked>> | 80% | 51,271 psi | 82% | 2500 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 45,818 psi | 73% | 2438 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 41,553 psi | 67% | 2431 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 42,206 psi | 68% | 2444 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 34,548 psi | 55% | 2323 fps | 99.1% |
| Vihtavuori N160 | <<locked>> | 82% | 32,808 psi | 53% | 2326 fps | 95.4% |
| Vihtavuori N530 | <<locked>> | 80% | 47,210 psi | 76% | 2546 fps | 100% |
| Vihtavuori N540 | <<locked>> | 80% | 40,654 psi | 65% | 2438 fps | 100% |
| Vihtavuori N550 | <<locked>> | 82% | 32,387 psi | 52% | 2333 fps | 95% |
| Vihtavuori N555 | <<locked>> | 90% | 30,966 psi | 50% | 2369 fps | 95.7% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 30,545 psi | 49% | 2254 fps | 96.8% |
| Winchester 748 | <<locked>> | 80% | 46,934 psi | 75% | 2589 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 40,640 psi | 65% | 2530 fps | 95.3% |
| Winchester StaBALL HD | <<locked>> | 94% | 28,906 psi | 46% | 2372 fps | 96.2% |
| Winchester StaBALL Match | <<locked>> | 80% | 43,134 psi | 69% | 2520 fps | 99.6% |
Recommended = one of the top powders for this cartridge and bullet combination.
ᴾ possible press load - work up slowly to this load while watching for signs of excessive pressure.
This overview compares 97 powders for .260 Ackley Improved loaded with the .264 | 135gr | TWENTY-NINE ERTP. Alliant Reloder-17 delivers the highest muzzle velocity at 2,835 fps; across all powders the maximum-charge window runs from 1,627 fps to 2,835 fps. Accurate 3100 gives the best case fill at 100 %, and 97 of the 97 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (430 MPa), the top charges use 56–90 %, leaving at least 10 % headroom. The 135.0 gr projectile in 0.265" calls for a 1:7.5 twist; slower twists will usually not stabilise this weight. Accurate 3100, Alliant Reloder-16, Alliant Reloder-23 reach 100 % fill or more at maximum charge, so these are compressed loads: they need a long drop tube to seat cleanly and react sensitively to the case capacity of your own brass lot. Alliant Power Pro 2000-MR, Hodgdon Superformance, Alliant Reloder-17 rank at the top here: for .260 Ackley Improved with the .264 | 135gr | TWENTY-NINE ERTP they combine a high case fill with complete burn and sit in the upper velocity band. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.